Re: [hylafax-users] High Error rates

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

On 2004.07.29 12:40 Stephen Carville wrote:
> On Thu July 29 2004 11:53 am, Lee Howard wrote:
> > On 2004.07.29 11:01 Stephen Carville wrote:

> > > Jul 29 07:00:30.66: [25453]: RECV send RTN (retrain negative)
> > > Jul 29 07:00:30.66: [25453]: <-- [9:AT+FRH=3\r]
> > > Jul 29 07:00:31.86: [25453]: --> [7:CONNECT]
> > > Jul 29 07:00:31.99: [25453]: --> [2:OK]
> > > Jul 29 07:00:31.99: [25453]: RECV recv DCN
> >
> > Did the sender call back and retransmit that page and the following
> > ones?
>
> Not as far as I can tell.  Should this be an automated response?

Yes, it should.  Each fax machine may work differently, but the sender 
certainly did not get a page-received confirmation, so (worst-case 
scenario of intelligent behavior) they may have seen some error on the 
fax machine indicating that they needed to re-send the fax.  Normally 
an intelligent fax machine will do this on its own.

> If
> it
> requires the sender to actually read the fax report and retransmit the
> page
> it may be hopeless with some of our customers.

That may be the case, and if it is, then you may have no recourse 
except to phone the sender and tell them to retransmit.

Note that if the sender's machine supports ECM, then you will be much 
better-served in these kinds of scenarios by using ECM yourself (i.e. 
Class 1 in HylaFAX 4.2.0).  The whole design of ECM protocol is more 
resiliant than without it.  Senders seem to tolerate a PPR (resend some 
portions of the page, only available in ECM) signal much more readily 
than an RTN (retrain and resend all of the page, only available in 
non-ECM) signal.

> Clients really disreagard the specifications?  Who'da thunk it...

Normally we can work around most fax machines misbehaviors in Class 1 
(Class 2 is up to the modem manufacturer).  However, when acting as the 
receiver and we have received a corrupted page and the sender is 
awaiting a response to it's post-page signal, we have limited choices: 
MCF (confirm receipt), RTN (reject page, request retrain and 
retransmit), DCN (disconnect), or hang up.  Confirming bad pages (doing 
MCF) would be the worst mistake we could do.  Hanging up or 
disconnecting would probably get the idea across, but at least sending 
RTN will permit a spec-following intelligent sender to cope.

Lee.

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